Circuit boards are typically made from a laminate of a layer of conductive metal, especially copper, and a substrate of insulating material. A pattern of etch resistant material is placed on the conductive metal layer by printing or by a photographic process. The conductive metal not covered by the etch resistant material is etched away chemically leaving on the insulating substrate metal that was protected by the resist material in accordance with the desired circuit. Although the printing and photographic processes are rapid and amenable to high volume production of electronic circuit boards, they are labor intensive for small numbers of circuit boards and therefore costly for the production of prototype and experimental circuit boards. Furthermore, because of the solvents used in the coating and development of the resist coatings, these processes are environmentally undesirable and require steps to recover the solvents in order to avoid pollution of the atmosphere. Also, because the waste etchant solutions contain ferric chloride, chromic acid, ammonium persulfate, or the like, costly steps must be taken to dispose of the waste solutions in order to avoid pollution of streams.
Electronic circuit boards have also been produced by processes not involving the use of resist materials and etching solutions. Thus, it is known to produce circuit boards by electronically guiding a rotatory bit. This process, however, produces coarse circuits inappropriate for production of today's high density circuits and also requires frequent replacement of the rotatory bit. Engraving processes are known, as are described in U.S. Pat. Nos. 3,183,745, 3,372,618, and 3,716,668 among others, whereby electrical circuit boards are produced using an apparatus having a cylinder on which is wrapped in side-by-side relation an image to be reproduced and a plate to be engraved with such image. The apparatus has a scanning member and a cutting member arranged adjacent respective portions of the cylinder for cooperation with the image and the plate to be engraved, respectively. If a flat circuit board is desired, it is necessary to engrave with this type of apparatus a suitable flexible plate, which after having a circuit cut into it, can be flattened and fastened to a rigid support.
There is also disclosed in U.S. Pat. No. 4,052,739 an electronic engraving system whereby an image of a person is converted by means of a television camera into electronic signals that can be used to produce the image in a plastic card such as a credit card. By such a system, there is used an engraving means comprising an engraving head having an engraving style adapted for vertical movement in response to the elctric signals and arranged to face an engraving table on which the plastic card is placed. The engraving table is reciprocated by a hydraulic cylinder from side to side. With each stroke the engraving head is displaced traversely with respect to the direction of movement of the engraving table.